Known personal care products, and especially incontinence undergarments and other items designed to absorb bodily fluids, typically are made with a top sheet material (also referred to as a cover sheet or liner), an absorbent core, or pad, and a liquid impervious back sheet. Some may also have a surge layer or other specialized layers between the top sheet and absorbent core. Absorption of fluid, comfort, and avoidance of leakage are the functions desired.
An ideal incontinence product, such as the personal care products discussed herein in conjunction with the present invention, would have no leakage and deliver comfort and discretion to the user. Current personal care products may have relatively high leakage and thus offer only modest protection to the consumer. Past product design has generally focused on three key causes of leakage: fluid does not absorb into the absorbent, fluid is absorbed into the absorbent but subsequently leaves it, or fluid never contacts the absorbent.
The specific reasons for leakage have been expressed further in terms of definitive mechanisms. A product, for instance, may not have suitable absorption due to localized saturation of the absorbent or insufficient area provided for fluid to contact the absorbent. The absorbent may not have a suitable driving force for absorption because its structures do not have the right balance of permeability and capillarity. The interfiber spaces may be fully or partially full of fluid. Fluid may contact the absorbent pad and run-off. The fluid may be too viscous or the pores or interfiber spaces are not large enough to allow fluid to pass through a surge layer to a subjacent absorbent layer.
In the past, the focus of the art has been on absorbency of the products. Liquid uptake rate and liquid volume capability of absorbent materials have in the past been the key considerations in providing an adequate time of retention. Thus, personal care product design has typically heretofore focused on the absorbent materials and their arrangement and concentration because leakage was considered to be a shortcoming of the functions of the absorbent materials, including the intake, distribution, retention and transfer rates, as well as shaping and conformability, of the absorbent materials.
Good fluid intake has been considered necessary in past garment construction. Intake includes the initial absorption of fluid into a dry product as well as the continued uptake of that fluid into the absorbent structure. Development of superior intake systems requires much effort and an understanding of environmental conditions including the nature of the fluid and its discharge. Developing functional intake structures requires an understanding of material characteristics and their interaction with the fluid as components and systems of components including interfaces and product design. Past product design efforts have included the arrangement and geometric design of material components and their interaction with the body and fluid.
Past product design efforts have also focused on the initial intake of bodily fluids into an absorbent article as a function of the characteristics of the liner or topsheet material and the upper absorbent layer. It has been recognized that the intake of bodily fluid into these materials is a function of the material characteristics including the ratio of void volume to fiber surface area, fiber orientation and fiber surface wettability. These intrinsic material characteristics can specifically define the more familiar material properties of permeability, capillarity and fiber wettability which can be calculated and measured by techniques well known in the art. Much effort has therefore been put into finding suitable intermediate layer and absorbent core matches for the characteristics of the liner to permit fluid communication and transfer. The task may be especially complicated considering the variation in liquid and solid flow rate, viscosity, location, surface tension, etc., from user to user and as these factors change for a user depending on the time of day.
As is known in the art, incontinence products such as diapers or other absorbent garments are often constructed from multiple layers of materials with each layer having a specialized function. For example, two common layers are the surge layer, specialized for the rapid uptake and distribution of bodily fluids away from the point of insult to the product and the absorbent layer which is specialized to hold and retain a high volume, or load, of liquid. However, the construction of garments with specialized layers, which may be functionally very efficient, may also lead to escalating product costs due to the expense of making and placing the multiple layers together in a garment. Thus, it is further desirable that the fluid handling, or distribution, layer and the fluid absorbent, or retention, layer be easily manufactured and incorporated into a personal care product in an economical fashion.
In each of the three key causes of leakage, time for absorption plays a critical role. A reason so much effort and expense has been spent on fluid distribution and absorption mechanisms of present personal care products is because the typical elasticized margin area of, e.g., a personal care garment, is leaky. Typically a marginal area is created with an application of pretensioned elastics which then contract, causing the marginal area of the garment to gather or shirr, creating a leaky seal against the body of the wearer. There remains a need for a personal care product that is able to contain body exudates in such a way as to keep the wearer protected from fluid being expressed out of the absorbent article over the amount of time necessary to allow complete absorption of bodily fluids, thus creating a “leakproof” garment structure.
Further, the known disposable or limited use garments; even when of a shaped or three dimensional design; are manufactured from flat materials such that when the garment is subsequently placed on the body, compromises of the fit between the marginal areas of the garment and the true body shape of the wearer provide avenues for leakage to the outside of the garment. This compromise of fit also affects the absorption and protection functions of the garment because the garment will tend to shift in relation to the body of the wearer when the wearer moves, affecting intended absorbent material placement and disrupting marginal seal placements against the body.
Thus, there further remains a need in the art to focus on exudate retention capability for incontinence garments, including a leakproof containment system, in order to lessen the burden on the uptake and absorbent materials of such garments.